A tape dispenser is known from DE-OS No. 31 09 735 which has an exchangeable supply spool of adhesive tape on a wind-off sleeve in a housing. The wind-off sleeve is formed integrally with a push button which is arranged so as to slide in the housing and under the force of a spring projects from the housing through a lateral opening. On the side of the housing opposite the push button there is a window with a tape pressing roller for applying adhesive tape unwound from the wind-off sleeve. When unwinding the adhesive tape from the supply spool on the wind-off sleeve, which requires the user of the device to press the push button against the force of the spring, the tape pressing roller cooperates with a tape guiding roller as well as with a tape deflecting roller. While the tape deflecting roller deflects the adhesive tape pulled off from the supply spool, the tape pressing roller presses the non-adherent side of the adhesive tape onto the support.
In order to automatically unwind the adhesive tape from the roll, which is secured against undesired rotation by an integral spring in the wind-off sleeve, on pressing the push button, the deflecting roller is pressed against the surface of the object to which the adhesive tape is to be applied and the leading end of the tape is struck down. By moving the device counter to the winding of the supply spool an adhesive tape strip of the desired length is unwound. Separation of the strip of adhesive tape applied from the supply roll is effected by a toothed rack on the push button which meshes with teeth on a disc having a cutting knife on its periphery. Pushing the push button causes the disc and cutting knife to turn clockwise, but when the pressure on the push button is released they move anti-clockwise as the spring relaxes until the cutting knife arrives at a position beneath the deflecting roller and separates the adhesive tape.
Apart from the very complicated and expensive separating mechanism, threading a new supply spool in is also exceptionally troublesome and requires much dexterity. Before the new supply spool can be placed on the wind-off sleeve it is necessary to unwind a strip of adhesive tape from the supply spool by hand and to place the leading end of the tape beneath the tape deflecting roller. The supply spool is then placed on the wind-off sleeve and is secured against undesired, independent rotation by the spring which presses a lug against the supply spool from the inside through the wind-off sleeve.
A further known unwinding device, closable with a lid, has inside its housing a wind-off sleeve over which exchangeable push-on supply spools of backing tape with double-sided adhesive tape adherent thereto (the backing tape with adhesive tape will hereinafter be termed transfer tape) and also a take-up sleeve. The two sleeves are operatively connected by cogwheels meshing with one another. Spaced from the two sleeves is an application roller having a part of its surface projecting outwards through a side opening in the housing wall, and having the transfer tape looped around it. When inserting a new supply spool, which has internal axial slots to receive external axial ribs on the wind-off sleeve to give a shape-locked connection, the leading end of the tape has to be placed around the application roller and--like film spools--threaded into a slit in the take-up sleeve. In addition, either before or after the threading, the adhesive film has to be removed by hand from the leading end of the transfer tape.
In this known unwinding device a brake lever is pivotably mounted on an axis in the housing floor. One end of this lever engages with a lug in the cogwheel of the wind-off sleeve, and the other end projects outwardly through an opening in the housing and forms a push button. By pressing the push button the lug is disengaged from the cogwheel of the wind-off sleeve and the sleeve is thus unlocked. By pressing the application roller against the object to which the adhesive strip is to be applied and simultaneously moving the device, the adhesive tape is separated from the backing tape and the backing tape is wound onto the take-up sleeve. On releasing the push button the lug engages with the cogwheel so that the wind-off sleeve is locked and the strip of adhesive tape is torn off. The use of this device thus also requires exceptional skill and dexterity when inserting a new supply spool and threading the leading end of the tape as well as in pressing down the brake lever with a finger when applying the adhesive strip.